Apparatus for starting and operating gaseous discharge devices



June 26, 1951 A. E. FEINBERG 2,553,293

APPARATUS FOR STARTING AND OPERATING GASEOUS DISCHARGE DEVICES Filed Dec. 29, 1949 2 Sheets-Sheet 1 i m mm w June 26, 1951 A. E. FEINBERG 2,558,293

APPARATUS FOR STARTING AND OPERATING GASEOUS DISCHARGE DEVICES Filed Dec. 29, 1949 2 Sheets-Sheet 2 j/zzuva a 7 07/ Patented June 26, 1951 1 APPARATUS FOR STARTING AND OPERAT- ING GASEOUS DISCHARGE DEVICES Albert E. Feinherg, Chicago, Ill., assignor to Advance Transformer (30.,

ration of Illinois Chicago, 111., a corpo- Application December 29, 1949, Serial No. 135,669

20 Claims.

This invention relates to apparatus for starting and operating gaseous discharge devices, such as fluorescent lamps. It is principally concerned with an electrical circuit for the so-called instant start type of lamp which requires an instantaneously high voltage suflicient to initiate the gaseous discharge in the lamp without the necessity of heating the filaments thereof. Once the discharge has been initiated, it is required of the apparatus that current flow be limited for the reasons well-known and inherent to gaseous discharge devices.

The problem of apparatus to be used in connection with instant start fluorescent lamps becomes more acute when a plurality of lamps is to be started for the simple reason that the ordinary application of a high voltage sufiicient to start one lamp instantaneously will cause the voltage to be divided between series connected lamps and the total voltage across either of the lamps will be insufiiicient to initiate the discharge.

This problem has been attacked by others, notably W. J. Karash, patentee of U. S. Patent No. 2,358,810 in which patent there are shown and described circuits for starting instant start lamps in which it is required that certain inductances and/or transformers be used in order to add the effect of line voltage to the induced voltage of an auto-transformer for starting the first lamp, and then to provide a maximum of reactive impedance across the second lamp.

One of the principal objects of my invention is to provide highly efficient apparatus for initiating the discharge of a plurality of instant start I gaseous discharge devices which will be extremely simple and not require expensive circuit elements in addition to an autotransformer.

In connection with the above object it is pointed out that my new invention utilizes a simple three winding transformer, the general construction of which is similar to that type of transformer used in circuits for starting common heated filament fluorescent lamps. Specifically, no special cores are required, no chokes or inductances need be used in the circuit, and one relatively cheap condenser may be used. The invention lies in the connections of the circuit, the manner of forming and the proportions of the windings, as well as other factors to be pointed out which give rise to the advantages of my invention.

Another object of the invention is to provide apparatus for initiating the discharge of a pair of instant start gaseous discharge devices seriatim and thereafter providing good regulation forthe flow of current therethrough.

A further object of the invention is to provide apparatus for initiating the discharge of a pair of gaseous discharge devices in which, following the initiation of such discharge and during the flow of current through both of said devices, the apparatus is constituted in effect a series circuit for said devices.

An object of the invention is to provide a novel arrangement of transformer windings for accomplishing the important functions of my apparatus.

A still further object of the invention is to provide apparatus of the character described which will draw a current from the line having good power factor characteristics.

Other objects will become apparent as the description proceeds in connection with which I have illustrated a preferred embodiment of my invention.

In the drawings:

Fig. l is a schematic electrical diagram showing the circuit or" my apparatus used to operate two fluorescent lamps.

Fig. 2 is a side elevational view showing the transformer construction capable of being used with my new invention.

Fig. 3 is a view similar to that of Fig. 2, but showing a modified form of my invention.

Fig. 4 is a schematic electrical diagram showing a modified circuit of my apparatus.

Referring to the drawings, the reference character it designates generally a transformer which forms an important part of my apparatus. Same is formed of three independently formed windings ll. l2, and i3 comprising a primary P, first secondary S1 and second secondary S2 respectively. All of the windings are mounted upon a central winding leg [4 which is pressed into an elongate shell [5, there being a magnetic shunt i5 and an air gap l! between the windings I and i The shell i 5 and the winding leg M are formed of electrical steel laminations in the usual manner thereby providing an iron core for the transformer H3.

The windings are mounted upon the shell 15 in a manner such that the primary II is in the center of the shell Hi, the second secondary i3 is on the left end of the shell I5 although mounted on the central winding leg I4, and the first secondary I2 is on the right end of the shell l5, separated from the winding H by the magnetic shunt I1, and thereby constituting the winding [2 a high leakage reactance. It is obvious that the windings l2 and !3 are both the winding 3 loosely coupled with the primary H, but that the first secondary i2 is what may be termed very loosely coupled to the primary, when comparing it with the second secondary coupling. Although both coils i2 and i3 have high leak age reactance, it may be advisable under certain operating conditions to place a small magnetic shunt i8 and a ap ll between coils H and [3 to provide additional leakage reactance as shown in transformer id, Fig. 3.

The windings H and [2, namely the primary l and the first secondary S1 are wound in the same direction to provide additive voltage, while the winding 23 comprising the second secondary S2 is wound in an opposite direction to provide bucking voltage.

Referring to Fig. 1, note that the windings I i, it, and it are connected in series providing junctures 2d and 2% therebetween, the right hand end of the transformer is being designated 22 and comprising the free end of the winding I; while the left hand end of the transformer being designated 23 and comprising the free end of H. Note that the windings are not mounted in the order in which they are connected.

-- There are shown two gaseous discharge devices, comprising a first fluorescent lamp 24 and a second fluorescent lamp 25. My apparatus "includes a condenser 25 in a load connecting lead 2'? which is connected to the juncture 2i. The-lamp 2!; is arranged in series with the condenser'2t, having the load connecting lead 2? from the condenser 25 connected to its right hand side, while the left hand side of the lamp -24 is connected via a load connecting lead 28 to juncture 23. Thus, it will appear that the first lamp 2 is connected across the primary and first secondary of the transformer 19, and

in series with the condenser 26. The second fluorescent lamp 25 has its right hand end connected by the lead 29 to the terminal 22, and its left hand end by lead as to the juncture 20. Thus it will be obvious that the second lamp is connected across the first and second secondaries. The very loosely coupled secondary i2 is common to the circuits of both lamps 2d and 25. The usual A. C. line 3| is connected across the primary H to provide the necessary power.

The first secondary Winding l2 has sufficient turns so that it steps up the line voltage of the primary ii considerably; in some instances almost four times. This voltage E5 is additive to the line voltage or rimary voltage Ep, and since windings H and 92 are in series and across lamp 2%, they add to provide igniting voltage for the lamp 2d. Although the winding is is so constituted that it provides an induced voltage ES of more than twice Ep, since its voltage is in opposed relationship to P and S1, the voltage across lamp 25, which is the sum of E5, and E5 will be very little prior to any current flow, .and certainly less than required to ignite the lamp 25.

The voltage across condenser 2% is negligible prior to ignition of lamp 2i, and hence the voltage Ep combined with E5, appears across lamp 2@, lights the'lamp, and causes current to commence flowing.

Current now flows in the circuit of lamp 2 2, and since the inductive reactance of the very loosely coupled secondary S1 is so great compared to the capacitive'reactance of the con denser 2c, the current of such circuit is lagging- The condenser 26 assists in shifting the phase of the voltage in the first secondary 12 by lowering the total reactance of the circuit of lamp 24. Such effect causes a higher flow of current and a consequently greater induced voltage across S1 which, of course, aids in causing lamp 25 to ignite.

I have found, that the current flow caused by the ignition of the first lamp 2i gives rise to voltage in the winding l2 whose phase is in effect reversed relative to the phase of voltage E and hence is additive relative to voltage E5 of winding i3, the secondary S2. This voltage is of such magnitude that the combined voltage appearing across lamp 25 is sufiicient to ignite the lamp and cause flow of current therethrough.

With current flowing through the both lamps, 2 and 25, the high inductive reactance of winding i2 serves to resist flow of current therethrough and thus the effective circuit is a series circuit with both lamps 2t and 25 which may be traced as follows: Juncture 23, lead 23, lamp lead 2'? and condenser 26, juncture 2i, winding it, terminal 22, lead is, lamp 25, lead 38, juncture The winding I2 is thus not an effective part of the operating circuit. The condenser 26 and inductive reactance of the apparatus may so neutralize their respective effects that the power factor of current drawn from the line leads 3! using my apparatus is almost unity. It is obvious that the lead 28 and the left hand one of the line leads 3! may constitute a single lead and that the lead 3% and the right hand one of the line leads 3! may also constitute a single lead.

In the event the current drawn from the line is leading, an additional gap 43 may be formed at the end of the winding leg is thereby increasing the leakage reactance of the apparatus while incidentally preventing saturation of the core from too greatly distorting the wave shape.

An example of apparatus embodying my invention readily could be constructed for initiating the discharge and providing regulation for a pair of fluorescent lamps known commercially as T-lZ lamps having an effective length of 48 inches and being rated at forty watts each. Such apparatus has been successfully produced and operated. The laminations of the shell i5 of the transformer had the dimensions of approximately two and one eighth by five and one quarter inches, and the stack thickness was approximately one inch. The magnetic shunt may be approximately one-half inch wide, and the gap 5? approximately .016 inch. The windows for the windings ii, l2, and is may be adjusted in size in accordance with the physical Volume of the windings.

The primary winding 5! was formed of 5&0 turns of number 25 wire; the first secondary winding E2 was formed of 2360 turns of number 35 wire; and the second secondary was formed of 1270 turns of numbe 2'? wire. The condenser 25 had a capacity of 2.6 microfarads and a rating of 440 volts maximum 'voltage. This apparatus operated in a highly satisfactory manner and the lamps 2t and 25 were ignited with such speed that it almost appeared that they ignited simultaneously when the power was turned on.

With a 118 volt 6O cycle A. C. line connected across the primary II, the voltage E5, was 405 volts, and the voltage Es, was 270 volts. E51 and Ep (the line or primary voltage) are additive winding 53 ,because the windings I l and I2 are formed in the same wound direction.

ings bear this out in the following manner: The

voltage measured from juncture 23 to juncture 2| was found to be 520 volts; the voltage measured from juncture to terminal 22 (across both secondaries l2 and 13) was found to be 150 volts; and the total sum of voltages across the entire transformer H3 taken from juncture 23 to 22 was found to be 27c volts. Since the type of lamp in the circuit requires approximately 450 volts to ignite, obviously the first lamp 24 will ignite since it has almost 520 volts appearing across its terminals, while the second lamp will not ignite because the total voltage across it is only approximately 150 volts. These measurements may be taken by removing the lamps 24 and 25 from the circuit.

Once the lamp 24 has ignited and the gas therein has broken down, current flows through that lamp, said current being limited by the reactance of the circuit including the high leakage reactance of the secondary !2.

With the lamp 24 operating, measurements can be taken of the voltages and currents in the apparatus by not placing the lamp '25 in the circuit, and such measurements are as follows: E is now only 210 volts and E59 appears to be 258 volts, while Ep remains at 118 volts; the voltage measured from juncture 23 to juncture 21 is now 162 volts indicating a radical change which I believe is caused by a phase shift having the effect of providing a voltage vector component additive to the voltage across $2 the second secondary winding l3, and bucking the voltage El across the primary P; the voltage across the lamp 25 measured from juncture point 20 to 22 is now 440 volts, or sufficient to ignite .the lamp 25; the voltage across the entire transformer Hi from juncture 23 to 22 is 315 volts; the voltage at the terminals of the lamp 24 is 140 volts and that across the condenser 26 is 105 volts; the current in the primary 1 i is found to be .8 ampere and the current in the lamp 2G is found to be .120 ampere.

The above measurements are static, that is,

made with only the lamp 24 operating and the lamp 25 not in the circuit. This situation will arise if the lamp 25 burns out, and it will be obvious from the values given that the apparatus is operating satisfactorily and may continue to do so, providing an important emergency feature for my apparatus.

It is probable that the initial surge of current occurring with ignition of lamp 24 will produce voltages in the first secondary l2 and the second secondary l3 whose sum will be considerably greater than 440 volts, but in any event, even the sum static voltage is sulficient to ignite lamp 25 when in place.

After lamp 25 has also become ignited, current flows in its circuit, and the condition of voltages and currents in the apparatus as determined by measurements is as follows: The primary voltage Ep is still 118 volts; the voltage across S1 the first secondary winding [2 is 310 volts; across the second secondary S2 the voltage is 308 volts; the voltage measured from juncture 23 to juncture 2| is 415 volts; the voltage across the second lamp 25 from juncture 20 to 22 is 107 volts; the voltage measured across the entire transformer II) from juncture 23 to 22 is volts; the voltage across the lamp 24 at its terminals is 107 volts; the condenser voltage is 418 volts; the current flowing in each lamp is approximately .435 ampere; and the current in the primary II is found to be .580 ampere. With both lampsv 24 and 25 operating the current measured in secondary S1 is only .030 ampere, which demonstrates that the high reactance of the winding 2 has the effect of forcing the entire circuit to act as a series arrangement so that the major flow of current is through the lamps 24 and 25, the winding I3, and the condenser 26. With such a circuit, the reactance occasioned by the presence of the condenser 26 is effective to counterbalance the inductive reactance of the transformer windings, so that there is very good power factor correction and the current drawn from the line 3! can be adjusted practically to be almost in phase with the line voltage.

It should be obvious that for diiferent types of lamps the circuit constants of my apparatus can be adjusted.

In the embodiment of my invention shown in Fig. 4, the connections of the circuit have been somewhat rearranged. The leads 28 and 30 have been interchanged and the windings of the transformer have been varied in accordance with the change. Thus, the transformer 60 corresponds to the transformer ll] of Fig. 1 and is constructed in quite a similar manner. The physical appearance is the same and hence is not shown here.

Electrically, there is a primary winding 6|, 2. first secondary winding 62, and a second secondary winding 63. The winding 62 is reverse wound relative to the other two winding GI and 63 and of such voltage relationship considering the number of turns relative to the primary winding 61, that there is a voltage developed thereacross that is sufficient to ignite a gaseous discharge device. The windings 6!, 62 and 63 are all connected in auto-transformer relationship. Thus, if the voltage required to ignite the gaseous discharge device is of the order of 450 volts, and the line voltage across the primary is 118 volts, then the number of turns of the first secondary 62 is approximately four times the number of turns on the primary 5!.

The primary winding 8! is connected to an A. C. line 64, and the second secondary 63 has sufficient turns that the sum of voltages across the primary, second secondary and the in-phase component induced. in the first secondary 62 after its gaseous discharge device has ignited will be suflicient to ignite a second gaseous discharge device. This shortly will be explained.

All three windings BI, 62 and 63 are connected in series, 61 and 62 being joined at 65, and 62 and 63 being joined at 6B. The left hand end or free end of the primary winding BI is connected at 6'! to the lead 68 and the right hand or free end of the second secondary winding 63 is connected at 69 to the lead 10.

Two gaseous discharge devices, such as for example fluorescent lamps i! and 12 are here shown connected to be ignited and operated by my apparatus. Lamp 7| has its terminals connected to the leads l3 and M which extend respectively to junctures 65 and 56. Lamp 12 has its terminals connected to leads 68 and 10 respectively. A condenser l5 is interposed in the lead 14.

The apparatus operates in a manner similar to the apparatus previously described herein. When the line voltage designated Vp (to distinguish it from the designation Ep previously used) is impressed across the primary winding 6|, a voltage V is induced in the first secondary winding 62 sufficient to ignite the lamp H and cause current to flow therein. It will be noted, that since the winding 62 is wound in an opposite direction to the winding 6!, the induced voltage is also opposite in direction. The current now flowing is limited by the impedance of the high leakage reactance winding 62 and the condenser 75. Due to this high leakage reactance of the winding 62 (same being arranged relative to the core and other windings of the transformer 58 in the manner that the winding 22 is arranged relative to the transformer Hi), there is a phase shift of the voltage in the winding 02 causing a reverse component of the voltage V51 to appear across the iunctures t5 and 65. The voltage component thus produced when added to the in-phase voltage V across the primary winding BI, and V5 across the second secondary winding 83 provides a voltage across the terminals of the lamp l2 suflicient toignite the same. Thereafter current flows in eifect through the lamps H and 12, the condenser 15, and the second secondary winding 63 in series. The reactance of the winding 62 is so high that it is by-passed by the current flowing through the lamps. The condenser l5 serves to increase the current flow through the lamp 1! when same has become ignited by voltage V5, and acts to correct power factor of the current drawn from the line 64. Other adjustments referred to herein can be made for power factor correction.

Asuccessful'example of my apparatus as described above in connection with Fig. 4, has been constructed and operated in connection with a pair of instant start fluorescent lamps. The physical construction of the transformer 60 was substantially the same as that of transformer ll! of the previously mentioned example. The discharge devices 71 and 12 again were T.-12, 40 watt, forty eight inch lamps. The primary winding 6| had 5'75 turns of number 26 wire, the reverse wound first secondary had 2900 turns of number 35 wire, the second secondary had 1420 turns of number 27 wire. With a 118 volt Vp impressed across the primary winding 6!, the secondary voltages prior to ignition of the lamps were 450 volts and 275 volts for V5 and V5 respectively. V5 was sufficient to ignite lamp 1 I, but the combined voltages across the terminals 69 and 67 were insufiicient to ignite lamp '12. After ignition of the lamp H, the voltage across terminals 61 and 6B was of the order of 450 volts and the lamp 12 became ignited. The lamps both operated at a voltage of about 107 volts and with a current of about .425 ampere flowing therethrough. The current in the first secondary winding 62 during operation was found to be only .035 ampere since practically all the current of the winding 63, namely .410 ampere was being bypassed through the lamp [2. The condenser 15, for this example, had a capacity of 2.3 microfarads and a rating of 440 volts. The current in the primary winding (H was found during operation to be .610 ampere.

It will be seen that the lamps of the circuit of Fig. 4 are ignited seriatim, the lamp H being first and thereafter being followed by the ignition of the lamp 12. It will also be obvious that the effective circuit after initiation of operation of both lamps is a series circuit which may be traced from one side of the primary winding 6| to the other as follows: juncture 61, lead 68, lamp 12, lead it, terminal 69, winding 63, juncture 66', lead M, condenser F5, lamp ll, lead 13, juncture 65.

I should like to emphasize that the nature of current and voltage in circuits involving gaseous discharge devices and the reactive elements is highly complex and the wave forms vary greatly from sinusoidal. It is difficult to theorize concerning the reasons for achieving the results al'- luded to herein, with certainty, and hence I do not desire to be bound by the explanation of theory to which I have attributed such results. The construction may be varied within the scope of my invention and without departing from the teachings thereof and perha s operating upon explained theory other than set forth. It is therefore desired to be limited only by the structure as set forth in the claims appended hereto and made a part hereof.

I claim:

1. Apparatus of the character described adapted to ignite and operate a pair of gaseous discharge devices from an A. C. source of relatively low voltage which includes an auto-transformer having a primary, a loosely coupled first secondary having one side connected to one side of said primary and in additive Voltage relationship thereto, and a loosely coupled second secondary having one side connected to the second side of said first secondary and in voltage buckin relationship to said primary, means including a capacitive reactor for connecting one of said devices across the primary and the first secondary, means for connecting the second of said devices across the first and second secondaries, and means for connecting said source across said primary.

2. Apparatus of the character described adapted to ignite and operate a pair of gaseous discharge devices from an A. C. source of relatively low voltage which includes a three-winding autotransformer having a primary, a loosely coupled additively wound first secondary having one end connected with the said primary, a loosely coupled second secondary, the said first secondary having its second end connected therewith, said secondaries being arranged in reverse voltage relationship one to the other, means including a capacitive reactor for connecting one of said devices across and the primary and the first secondary, means for connecting the second of said devices across and the first and second secondaries, and means for connecting said source across the primary, the secondaries having a turn relationship to the primary to cause seriatim ignition of said first and second devices, and the reactance of the first secondary being very high relative to the second secondary whereby after the said devices are both operating the apparatus will form in effect a series circuit connected across the primary, said circuit including the devices, the capacitive reactor, and the second secondary.

3. Apparatus of the character described adapted to ignite and operate a pair of gaseous discharge devices from an A. C. source of relatively low voltage which includes an auto-transformer having a primary, a loosely coupled first secondary having one side connected to one side of said primary and in additive voltage relationship thereto, and a loosely coupled second secondary having one side connected to the second side of said first secondary and in voltage bucking relationship to said primary, means including a capacitive reactor for connecting one of said devices across the primary and the first secondary,

means for connecting the second of said devices across the first and second secondaries, and means for connecting said source across said primary, the first secondary being of higher reactance than the second secondary and being more loosely coupled to the primary than is the second secondary.

, 4. Apparatus of the character described comprising an auto-transformer for igniting and operating a pair of gaseous discharge devices from a source having a voltage substantially lower than the igniting voltage of either of said devices, and having three windings connected one after the other and comprising respectively, a primary, a first secondary, and a second secondary, leads for extending circuit connections to one of the devices across the primary and first secondary together, leads for extending circuit connections to the second of said devices across the secondaries together, the primary and first secondary having sufiicient turns to provide a voltage for igniting the first of said devices when the primary is energized by said source, and ,the secondaries having sufficient turns to provide a voltage for igniting the second device but being inductively arranged additively to combine their voltages only after ignition of said first device, and means comprising a magnetic shunt establishing a high leakage reactance in said first secondary to prevent substantial passage of current therethrough after ignition of both devices so that the devices and second secondary are connected in an effective series cirsuit.

5. Apparatus for igniting and operating a pair of gaseous discharge devices from an A. C. source of relatively low voltage which comprises an auto-transformer having a primary, a loosely coupled high leakage reactance first secondary of greater than unity turn relationship to the primary and arranged additively relative thereto, and a second loosely coupled high leakage reactance secondary of greater than unity turn relationship to the primary but arranged bucking relative thereto, a first juncture between the primary and first secondary, and a second juncture between the first and second secondaries whereby said primary, first secondary and second secondary are connected one after the other, said source adapted to be connected across the primary, means for connecting one of said devices from the free end of the primary to the second juncture including a capacitive reactor, and means for connecting the second of said devices from the first juncture to the free end of the second secondary, the resulting voltage relationships being such as to ignite the first device, then the second device, and then to establish a series path for the current through the devices, the second secondary, and the capacitive reactor.

6. Apparatus of the character described for igniting and providing operating regulation for a pair of gaseous discharge devices from a source of alternating current whose voltage is substantially less than the starting voltage of either of the devices, which includes reactive means having a primary winding, first and second secondary windings loosely coupled to the primary and to one another, the coupling of the first secondary winding being substantially looser relative to the other two windings whereby to constitute same a higher leakage reactor, the second secondary winding being arranged in bucking voltage relationship to the other two windings, the windings being connected in series with the first two, a capacitive reactor having one side therehaving a primary,

or connected to the common juncture of the secondaries, means for connecting the first of said discharge devices between the second side of the capacitive reactor and the free end of the primary winding whereby said first discharge device is in series with the primary, first secondary, and the capacitive reactor, means for connecting the second of said discharge devices across both secondaries, said secondaries having a turn ratio relative to the primary winding to cause ignition of the first of said devices when the primary is connected with the said source followed by ignition of the second or" said devices, followed by effective series operation of both devices.

7. Apparatus for igniting a pair of instant start gaseous discharge devices and operating the same with desired regulation from an A. C. source of voltage insufiicient to ignite either device comprising an auto-transformer, having a primary adapted to be connected across the source and establishing a voltage equal to the source therein, a first inductively reactive portion of said transformer of high leakage and of relationship relative to the primary for having a voltage induced therein substantially greater than the source voltage whereby the combined voltages will suffice to ignite one of said devices, means for impressing the combined voltages of the primary and the said first reactive portion across said device for igniting same, a second inductively reactive portion of said transformer of high leakage and of relationship relative to the primary for having a voltage induced therein greater than the source voltage, but bucking the same, said first portion producing after ignition of the first device a voltage having a component additive relative to the said bucking voltage whereby the sum of said after ignition voltage and bucking voltage will be sufiicient to ignite the second device, and means for impressing the said sum upon the second of said devices to ignite the same.

8. Apparatus for igniting a pair of gaseous discharge devices and operating the same from a low voltage A. C. source which comprises a transformer having three windings comprising a primary, first secondary and second secondary, the secondaries being in reverse voltage relationship one to the other, lead means for forming a series circuit for one of said devices across two windings, lead means for forming a series circuit for the other of said devices across two windings, the first of said secondaries being common to each circuit and having relatively high inductive reactance whereby to impede fiow of current therethrough after ignition of both devices and forcing the current to flow in series through the devices and the second secondary.

9. Apparatus of the character described adapted to ignite and operate a pair of gaseous discharge devices from an A. C. source of relatively low voltage which includes an auto-transformer a first secondary and a second secondary, both secondaries being loosely coupled to the primary, the first secondary being connected between a terminal of the primary and a terminal of the second secondary, the first secondary being arranged in bucking voltage relationship to the primary while the second secondary is arranged in additive voltage relationship to the primary, leads having a capacitive reactor for connecting one of said devices across the first secondary, leads for connecting the sec- 11 ond of said devices across all three of said windings, and line leads for connecting the source across the primary, the secondaries having a turn relationship to the primary whereby the first of said devices'will be ignited when power is applied to the primary by said source causing a flow of current through said first secondary which in turn will produce a component of voltage in said first secondary in phase with the voltages of the primary and second secondary such that sum of voltages across the three windings after ignition of said first device is sufficient to ignite the second of said devices, the said first secondary having a relatively high leakage reactance greatly to limit the fiow of operating current therethrough whereby after ignition the said devices will operate as though in efiect they are connected in series with only the second secondary and the primary.

10. In apparatus of the character described for igniting and thereafter regulating the operation of a pair of gaseous discharge devices from a source of A. C. voltage substantially less than the igniting voltage of either device, a multiple winding auto-transformer having a primary and two secondaries, the two secondaries being arranged in voltage bucking relationship one to the other with reference to a circuit containing both secondaries, means including a capacitive reactor for connecting one of said devices across a, part of the said auto-transformer including at least the, first secondary and excluding the second secondary, means for connecting the second of said devices across windings of said transformer including at least both of said secondaries, said windings and primary having a turn relationship to produce upon energization of said primary a voltage across the first device sufiicient to ignite the same, but across the second device insumcient to ignite the same, said first secondary having a high leakage reactance whereby after ignition of said first device there will be a phase shift in the voltage thereof providing a component additive to the second secondary whereby to increase the voltage across said second device to a value sufficient to ignite the same.

11. Apparatus for igniting a pair of gaseous discharge devices and operating same from a low voltage source of alternating current, which comprises a transformer having an iron core, three windings mounted upon the core and comprising a. primary, a first secondary, and a second secondary, means for connecting said devices in two separate series circuits across two parts of said transformer, one part including at least said first secondary and excluding said second secondary, and the second part including at least both secondaries, whereby the said first secondary is common to each of said circuits formed, said secondaries being arranged in voltage bucking re lationship one to the other on said core with said first secondary physically spaced from the other two windings to provide very loose coupling and high leakage reactance therein during operation, whereby current flow will be impeded therethrough during operation forcing fiow of current substantially to by-pass the same to provide an effective series circuit through said devices and the said second secondary.

12. Apparatus of the character described comprising an auto-transformer for igniting and operating a pair of gaseous discharge devices from a source having a voltage substantially lower than the igniting voltage of either of said devices, and having three windings inductively arranged one relative to the other and comprising a primary, 9, first secondary, and a second secondary, means for connecting one of said devices in a circuit across the primary and first secondary together, means for connecting the second of said devices in a circuit across the secondaries together, the secondaries bein arranged with their open circuit voltages opposing one another in said mentioned circuit, the primary and first secondary having suificient turns to provide a voltage for igniting the first of said devices when the primary is energized by said source, and the secondaries having sufiicient turns to provide a voltage for igniting the second device but being inductively arranged additively to combine their voltages only after ignition of said first device, and means comprising a magnetic shunt establishing a high leakage reactance in said first secondary to prevent substantial passage of current therethrough after ignition or" both devices so that the devices and second secondary are connected in an effective series circuit.

13. A lamp ballast for operating two discharge devices comprisin a primary, a first secondary, a second secondary, a pair of terminal leads for extending connections to a discharge device, the terminal leads and the secondarie being so connected that when a load is across the terminal leads it forms a loop with the two secondaries and the voltages of said secondaries in opposition to one another in said 100p prior to the fiow of current through the secondaries whereby at that time the voltage across the terminal leads is substantially the difference between the voltages across the two secondaries, another terminal lead extending from the loop for connection in a circuit leadin to another discharge device, the loop circuit being connected in circuit with the primary at a point on the loop such that only the first of the two secondaries lies between that point and the other terminal lead and that first secondary being in step-up auto transformer relationship to the primary, a magnetic structure coupling the primary with the two secondaries, the secondarie being more closely coupled to the primary than to one another, said first secondary taking a lagging current upon starting of current fiow therethrough whereby after current commences to fiow therethrough the direction of the voltage across the first secondary is substantially reversed with respect to the voltage induced in the other secondary and the voltage across said first terminal leads becomes substantially the sum of the voltages across the two secondaries, said first secondary being of substantially higher reactance than that of the other secondary whereby in operation of the ballast said first terminal lead in series with the second secondary are shunted by the higher reactance secondary, and the circuit which includes the first terminal leads in series with the secondary and shunted by the higher reactance secondary is in series with said other terminal lead.

14. A lamp ballast for operating two discharge devices comprising a primary, a first secondary, a second secondary, a pair of terminal leads for extending connections to a discharge device,

the terminal leads and the secondaries being so connected that when a load is across the terminal leads it forms a loop with the tw secondaries and the voltages of said secondaries in opposition to one another in said loop prior to 7; the flow of current through the secondaries whereby at that time the voltage across the terminal leads is substantially the difference between the voltages across the two secondaries, another terminal lead extending from the loop for connection in a circuit leading to another discharge device and including the primary, the loop circuit being connected in circuit with the primary at a point on the loop such that only the first of the two secondaries lie between that point and the other terminal lead and that first secondary being in step-up auto transformer relationship to the primary, a magnetic structure coupling the primary with the two secondaries, the secondaries being more closely coupled to the primary than to one another, said first secondary taking a lagging current upon starting of current fiow therethrough whereby after current commences to flow therethrough the direction of the voltage acros first secondary,

is substantially reversed with respect to the voltage induced in the other secondary and the voltage across said first terminal leads becomes substantially the sum of the voltages across the two secondaries, said first secondary being of substantially higher reactance than that of the other secondary whereby in operation of the ballast said first terminal leads in series with the second secondary are shunted by the higher reactance secondary, and the circuit which includes the first terminal leads in series with the secondary and shunted by the higher reactance secondary is in series with said other terminal lead, and a condenser in series with said first secondary and of a capacity reactance less than the inductive reactance of the first secondary.

15. A lamp ballast for operating two discharge devices comprising a primary, a first secondary, a second secondary, a pair of terminal leads for extending connections to a discharge tube, the terminal leads and the secondaries being so connected that when a load is across the terminal leads it forms a loop with the two secondaries and the voltages of said secondaries in opposition to one another in said loop prior to the flow of current through the secondaries whereby at that time the voltage across the terminal leads is substantially the difierence between the voltages across the two secondaries, another terminal lead extending from the loop for connection in a circuit leading to another discharge device, the loop circuit being connected to the primary at a point on the loop such that only the first of the two secondaries lies between that point and the other terminal lead and that first secondary being in step-up auto transformer relationship to the primary, a magnetic structure couplin the primary with the two secondaries, said structure including a rectangular shell and a. central winding leg between the transverse ends of the shell, the secondaries being at the ends of the central leg and the primary being between the secondaries so that the secondaries are more closely coupled to the primary than to one another, magnetic shunts bridging a, major portion of the space from the central leg to the shell on opposite sides of the primary to provide high leakage reactance for the secondaries, said first secondary taking a lagging current upon starting of current passing therethrough whereby after current commences to flow therethrough the direction of its voltage across the first secondary is substantially reversed with respect to the voltage induced in the other secondary and the voltage across said first terminal leads becomes substantially the sum of the voltages across the two secondaries, said first secondary being of substantially higher reactance than that of the other secondary whereby in operation of the ballast said first terminal leads in series with the second secondary are shunted by the higher reactance secondary, and the circuit which includes the first terminal leads in series with the secondary and shunted by the higher reactance secondary is in series with said other terminal lead, and means for preventing saturation of the central core leg adjacent the second secondary comprising a bridged air gap between the adjacent end of the core leg and the shell.

16. Apparatus for igniting a pair of discharge devices and operating same from a low voltage source of alternating current, which comprises a transformer having a primary, a first secondary, and a second secondary, leads for connecting to a discharge device, said leads being in a series circuit including the primary and only the first one of the two secondaries, leads for connecting another discharge device in a loop which includes both secondaries with their open circuit voltages in opposition in said loop and which excludes the primary, the first secondary being more closely coupled with the primary than it is with the second secondary and havin a relatively high inductive reactance whereby to impede flow of current therethrough after ignition of the devices, and thereby forcing the current to flow in series through said devices and the second secondary.

17. A structure as defined in claim 11 in which said first part comprises said first secondary winding and excludes the primary winding.

18. A structure as defined in claim 11 in which said second part comprises all three of said windings.

19. A structure as defined in claim 11 in which said first part comprises said first secondary windin and excludes the primary winding, and said second part comprises all three windings.

20. A structure as defined in claim 11 in which said first part comprises said first secondary winding and excludes the primary winding, and said second part comprises all three windings, and said mean for connecting the device including said first secondary winding includes a condenser.

ALBERT E. FEINBERG.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,854,490 Sola Apr. 19, 1932 1,873,975 Meyerhans Aug. 30, 1932 2,354,879 Ranney Aug. 1, 1944 2,366,768 Boucher Jan. 9, 1945 2,370,635 Bridges Mar. 6, 1945 2,382,638 Keiser et a1. Aug. 14, 1945 2,436,399 Nathanson Feb. 24, 1948 2,436,400 Nathanson Feb. 24, 1948 2,510,209 Bridges June 6, 1950 

